The very potent biological activities attributable to compounds structurally related to the active ingredients of Cannabis sativa L. has generated a great deal of interest and research during the past several years. Numerous chemical modifications has led to the discovery of extremely potent compounds of the cannabinoid family which are clinically useful. U.S. Pat. Nos. 3,928,598, 3,944,673 and 3,953,603 describe several hexahydrodibenzo[b,d]pyrans which are particularly useful in the treatment of anxiety, pain and depression. Novel methods of preparation of such compounds has been summarized by Archer et al. in J. Org. Chem., 42, 2277 (1977).
While a great deal of synthetic chemistry has been devoted to the modification of the substitution patterns of pharmacologically active dibenzo[b,d]pyrans, very little chemical research has been directed to structural modification of the basic tricyclic nucleus of such compounds. The synthesis of certain B-ring homocannabinoid derivatives, i.e. dibenz[b,d]oxepins, recently has been disclosed by Matsumoto et al., J. Med. Chem., 20, 25(1977) and by Freedman, U.S. Pat. No. 3,859,306. Similarly, benzopyran-type compounds having a 5 or 6-membered C-ring have been described in U.S. Pat. Nos. 2,972,880, 4,051,152, 4,007,207 and 4,025,630.
It is an object of this invention to provide 6,6,7-tricyclic compounds which are structurally similar to dibenzo[b,d]pyrans and which are extremely active pharmacologically while at the same time not causing some of the deleterious side effects often observed with conventional marijuana-like compounds.